A couple of years ago, the then editor of the Daily Telegraph asked me to revise the paper's style book. Having done so — and it was a task far more complex and exhausting than I had imagined it would be — I started to send out emails every three or four weeks to my colleagues to highlight mistakes they were continuing to make. The newspaper market is fiercely competitive. We need every reader we can get, and none of us wants to hear of somebody cancelling his subscription because he is irritated by the journalists' command (or otherwise) of the English language.

A good grasp of grammar helps one commit fewer (not less) mistakes

These emails ended up being leaked into the outside world and on to the internet. They were spotted there by an editor at Random House who asked me to compose a more detailed book on how to write correctly. I did so with trepidation: not merely because we all make mistakes, but because I was well aware that there is a school of thought that says there is no such thing as writing correctly. Nonetheless, the fruit of my labour, Strictly English (Random House, £12.99), has just been published.

I have been a professional writer, both of journalism and of books, for nearly 30 years. I started out as a sub-editor on a scientific magazine. Our contributors' English was not inevitably wonderful and it was my task to improve it. To be sure I was doing so, I swotted up on two aspects of English: its grammar and its style. For the first, I read the usual Fowlers, Partridges and Gowerses; for the second, I drew on my degree in English and tried to discriminate between those who wrote badly and those who wrote well. A prejudice for short sentences, short words and concision came from an extensive reading of George Orwell, whom I still rate as the finest writer of English prose in the last century.

This training has carried me through my career, and its principles have informed the book I have just written. I found, however, when writing the book that I could not merely take what I thought was right, both in grammar and in the use of words, and inflict it upon others. I found I needed to try to justify myself first. Therefore, my opening chapter briefly discusses the attempts to codify the grammar of our language and the meaning of words that led in 1928 to the completion of the first edition of the Oxford English Dictionary and, on the way, to an attempt by C. T. Onions, Otto Jespersen and others to settle the grammar. I came up against the beliefs of linguists and other radicals that our language, being organic, will evolve: and I had to make an argument for why words should not change their meaning for reasons of ignorance (as opposed to reasons of necessity) and why the logic of grammar should remain inviolable. Many academic linguists will simply not agree. Tough: my book is not aimed at them.

Like many of my generation, I was fortunate to study foreign languages at school: in my case French, Latin and Greek. As a result, I learned the rules of grammar. I learned when to use an adjective and when an adverb. I learned about the sequence of tenses. I even learned about the subjunctive. But what of those who have never had a grammar lesson in their lives? What of those whose spelling has never been corrected? What of those who use words entirely wrongly? I am well aware that to many this simply does not matter: if they can be understood by interlocutors or someone reading their emails, that is all that matters. Yet do we wish our language to be corrupted by ignorance, as opposed to changing legitimately when the need dictates it? I suspect we don't.

There is, though, a more practical point about language. We live in an old country and therefore in a class-ridden society. However much we may protest to the contrary, we still judge people by how they speak. If our command of English is good enough to spot grammatical errors in the speech or writing of others, or to note that someone has misused a word, then we shall come to a certain conclusion about them. If the person who makes the error is one who seeks to present an air of credibility, then he will be damaged by his slip. Many people are conscious of this, which is why they read books such as mine in order to try to ensure that they avoid exposing themselves in this way.

I run the graduate trainee scheme at my newspaper. The people who vet the applications are under instructions to reject those with grammatical errors or spelling mistakes on the grounds that someone who would be a professional writer in the high-pressure atmosphere of a newspaper should not be prone to making mistakes: and, indeed, those filling in application forms or writing covering letters for them should have all the time in the world to check their work before submitting it. In this way those who cannot spell or write English grammatically have their life chances harmed as a result. I wonder whether this ever occurs to the teachers who feel no need to correct spellings or solecisms?

We ought also to make a judgment about the quality of someone's writing and how it reveals the quality of his thought process. Someone who writes in a stream of clichés is not really thinking at all. Someone who fails to see the logic of the rules of grammar may well fail to see the logic of a lot of other things, too. Someone with these failings is unlikely to be able to comprehend, or have an accurate appreciation of, much of English literature, thereby being denied one of the greatest intellectual pleasures of our culture. Such people are unlikely ever to be persuasive in their communications with others, at who knows what cost to them. The Marxist educationalists have done the products of their system no favours in this respect.

To promote my book, I went a few weeks ago to a very good comprehensive school in Suffolk to talk to the pupils about how they regarded correctness in English usage. They accepted there was a standard. They all recognised that their chances of getting a place at a good university, or of getting a good job, could still be handicapped by a poor grasp of English. They said their spelling was corrected at school but not their grammar. That, they agreed, was something their parents did. Will the next generation of parents be able to do this? Or are we about to have a two-tier language: one that is spoken and written in accordance with the rules by a tiny percentage of highly-educated people, and one that is a free-for-all, and in complete decay, by everybody else? The result of having a culture dominated by the second is that it will fragment further. It would be bad enough for us to be like Tsarist Russia, where a small elite spoke French and the masses what was considered to be the crude and coarse mother tongue. It would be worse if we ended up with no mother tongue at all, but a series of argots based on geographical or social location, so that an American or Australian might be infinitely more comprehensible to an educated user of English than someone from a housing estate in Doncaster or Portsmouth.

The media are the guardians of the language, in default of the schools. Yet while I was writing my book I heard a reporter on BBC Radio 4's Today programme, normally a bastion of correct English, talk of someone "flaunting" the rules. He meant flouting. However, when I looked up the verb "flaunt" in the online edition of the OED, I found it explained that it was sometimes used instead of "flout". Radicals would not mind this: it is, in their view, a justified change in the living language. Yet it is a pointless change. "Flout" is a perfectly good word. It does not need a synonym in "flaunt", especially such an illogical one. "Flaunt" has not been adopted as a synonym for reasons of necessity. It has come to be one (and please forgive me for not mincing my words) because of the pig ignorance of some people who choose to use it as such. And, no doubt, those users were never told by their teachers not to do so.

The determination not to teach English properly in schools is all part of the determination not to enforce rigid standards, and to force children to make the intellectual effort to comply with them. It is why the standard of the grades of public examinations has had to be systematically lowered since the 1970s in order to ensure that a respectable number of children pass them. Socialism loves such a doctrine, because the more stupid people are the easier they are to control. This is especially true if they leave school ostensibly with a GCSE or even an A level in English, but are still largely inarticulate and in some measure illiterate. A solid and accurate grounding in English should be the basis of all other study. It should be the basis of a successful career and of continuing education, usually autodidactically, after formal education is over. To allow it to be otherwise is to create a people in whom intellectual curiosity has been killed and for whom effective communication is an unknown land. We should be ashamed that our education system has brought people down to this level. It is time we resolved to force our children, and in the first instance their teachers, to make that effort.